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Questions tagged [eyes]

The discussion of the anatomy and evolution of eyes. Consider using the "vision" tag for questions regarding how the brain interprets information from the eyes.

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Does Rüppell's Griffon Vulture Have Greatest Vision Acuity? (Small Carrion Spotted at 10 km+?)

Synopsis: Some sources seem to imply the Rüppell's (griffon) vulture (Gyps rueppelli) can see objects at a distance in excess of 10 km -- roughly three times the ...
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2answers
335 views

Cerebral activity during exposure to non - visible light

Our eyes only have the ability to sense light within a certain spectrum. My understanding is that particular frequencies energize specific cells in our eyes, each responsible for a different "color". ...
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1answer
262 views

What is the mass of a human retina?

I'm struggling to find a reference for the mass or density of a human (monkey or rabbit would also work) retina. I'd appreciate any help!
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250 views

Why bipolar neurons in retina transfer information via graded potentials?

Why should bipolar cells prefer graded potentials to action potentials? My attempt: I know that graded potentials are better in processing information since stimulus is directly proportional to ...
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1answer
961 views

If mantis shrimp have 16 photoreceptors then how many other colors on the spectrum are there? [closed]

Mantis shrimp have 12 to 16 photoreceptors and humans have 2, and in rare occasions even 3. But if mantis shrimp can see 16, how many other colors are out there? How many photoreceptors is possible? ...
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2answers
998 views

Is the bipolar neuron of the retina considered a sensory neuron?

Any neuron that participates in sending impulses from receptors to CNS are referred as sensory neurons. But I often see bipolar neurons of eye(which according to the above definition should be sensory ...
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0answers
55 views

What do I need to do to make a Reverse colorblind image?

As a 15 year suffering from moderate Protan colorblindness, I've wanted to find any advantages of colorblindness. I discovered there are Reverse colorblind tests, which only colorblind people are able ...
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60 views

Are there people who can change one of their eyes' depth of focus, while not changing the other eye's?

Are there people who can change one of their eyes' depth of focus, while not changing the other eye's depth of focus, without any surgical or other external mechanical intervention? Edit: let's ...
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1answer
846 views

Can frogs see clearly under and above water?

If humans attempt to see underwater, the image is blurred due to refractive differences in air and water that disrupt the normal refractive effect of the lens in the eye. A diving mask overcomes this ...
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1answer
67 views

Oculus rift (or, what do other eye placements see?) [closed]

I could be WAY out of line in the placement of this question, but here goes: Everyone I'm sure has heard of the Oculus Rift or any of the several other VR headsets making their way around. It ...
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2answers
281 views

How do S and L cone cells sense colors like deep blue and red beyond their peak?

So I found this diagram of retinal cone cells: It looks like the S, M, and L cones peak at blue, chartreuse and orange, respectively. If so, how do we see colors past 575 nm and before 445 nm? If the ...
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2answers
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How are colors outside the standard RGB color scheme perceived?

I found this image in a German book about biology. It's called DIN 5033 and represents the RGB color scheme. What colors are outside the RGB scheme, i.e., in the black areas of the picture?
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1answer
482 views

How are cells of the cornea transparent?

We know that cells have mitochondria, chromosomes and other organelles so that's why they are opaque but can you say how the cells present in the eye cornea are transparent and allow light to pass ...
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0answers
42 views

Why do eyes close when we sneeze? [duplicate]

It is a behaviour that is very difficult to control. We can't sneeze with eyes open. Is it a reflex of brain to protect the eye from possible injury in sneezing motion or the neural pathway for ...
9
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1answer
465 views

Do other animals suffer from myopia or hypermetropia?

Mammals have eyes similar to humas and many other animals like octopuses have a lens in the eye. So do they have such eye defects? If yes, how do they overcome it? Do they feel selection pressure ...
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0answers
84 views

Why do most fish move fins orthogonally with their axis of symmetry?

So recently I read the question why are most fishes vertical (in the sense of distribution of their body mass) and it got me thinking what is the reason behind the direction they move their fins. My ...
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1answer
324 views

How is color information transmitted from the eye to the brain via the optic nerve? [closed]

I would presume that is has something to do with synapses and specific chemicals starting specific charges through the optical nerve's sub-components, and that this is somehow interpreted by the brain ...
7
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2answers
330 views

Why can't we half-close our eyes?

Can we half-close our eyes such that they don't vibrate? If not, then why we are unable to half-close our eyes properly? Alternatively, why isn't it possible to keep the upper eyelid close to the ...
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4answers
3k views

What are the floating translucent little objects called in the field of view? [duplicate]

Sometimes we see these small translucent shapes moving by when the eyes are open. When the eyes are moved they seem to follow that movement, but with a certain delay, as if they are floating in a ...
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69 views

Do squids or octopus suffer from myopia(hyperopia)? Do other vertebrates get myopia(hyperopia)?

Both vertebrates and cephalopods evolved very sophisticated camera-type eyes, and both are capable of focus. But it also pose a risk of inability of focusing, such as myopia in human. So is myopia a ...
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2answers
1k views

Could there be any effects from low powered infrared being used to track eye movements long term?

Basically, looking into infrared LED's and a camera with an infrared bandpass filter for tracking eye movements; my concerns are whether there would be any potential negative long term effects from ...
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0answers
230 views

Is Near-infrared focused light safe for your eyes?

I found a new product, but I'm afraid it's not safe. Can you help me understand what the safety limits are when it comes to near-infrared light focused on your eyes is? I'm assuming the wavelength ...
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5answers
1k views

What is the smallest difference in light wavelength that the human eye can detect?

Is there a lower limit to the difference in wavelength (colour) our eyes can detect? If so, is this consistent between individuals? Are there any other traits correlated with precise colour vision?
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1answer
121 views

Widest angular of binocular vision [closed]

Which out of eagle, rat, duck or owl has the widest angle of binocular vision? I am pretty sure it's not rat and duck but I am confused between owl and eagle. Can anybody help me figure out which ...
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1answer
3k views

What is the rest state for eyelids - Open or Closed?

If one were to not apply any efforts on the eyelid muscles, will they remain open or closed? In movies when we see a person die, either case could happen - their eyelids could be open or closed when ...
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1answer
2k views

What is the connectivity between on-center & off-center bipolar cells?

Do rod-photoreceptors only form synapses with on-center bipolar cells (and on-center ganglion cells in the next step)? If so, why is that? Why do rod-cells only connect to on-center cells, while the ...
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1answer
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Can “red” cone cells actually see much red light?

In electronics, the most common color scheme is the "red-green-blue" (RGB) scheme. This choice is often justified by claiming that the long- (L), medium- (M), and short- (S) type cones in the human ...
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0answers
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Why does vision gradually becomes dimmer in bright setting?

I don't know if this is only happens to me, but if I am in a well lit room and I stare at one point or just look at one area without moving my eyes around my vision in that specific light setting ...
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1answer
2k views

Why can myopic eyes focus on nearby objects, but not on distant ones?

In myopic eyes, far away objects get blurry. I understand that myopia means that the focus of the lenses concentrates light at a point in front of the retina, thus by the point the light rays reach my ...
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3answers
9k views

Why can't we feel pain when the eye lid touches the eye ball?

When I press a finger on a closed eye lid it means the eye lid touches eye ball, then I didn't feel any pain. Now I open my eye lid, then I small touch(not press) the eye ball, it gives me pain, why ...
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1answer
131 views

Accommodation mechanism. [closed]

Can anyone explain how contraction of the ciliary muscles causes relaxation of the zonules? Please explain it anatomically i.e. the attachments of ciliary muscles and its relation with the ...
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0answers
523 views

Do blurry images cause eye strain? At what point is an image so blurry the eye stops trying to focus it?

I'm a user experience designer concerned about a new trend of blurring screens when showing a lightbox/dialog box over top (see below). From what I know, blurry images cause the brain to work hard ...
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1answer
1k views

Can a color-blind person see color with filter glasses?

Why does color vision improve in color-blind persons using these filter glasses from Enchroma? Will a color blind person be able to see the same colors on a television? I'm asking, because the colors ...
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0answers
284 views

Would a transparent iris serve its purpose?

The function of the iris is to regulate the aperture of the pupil. How does the iris obstruct light? Is it due to the pigment present in it? Or is it just due to the sheer presence of it? I am doing ...
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1answer
284 views

What really is color and how do we perceive it?

How do our brains actually transform the information that the cones in our eyes receive into the different colors that we can see and imagine?
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1answer
5k views

Why does my eyes see a red spot when over exposed to light?

When I looked into my projector when it was on the blue screen it left a red spot in my vision. I should not have tried it but all the colors left a red spot. Why not a blue or yellow spot was left?
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1answer
669 views

do game animals have poor eyesight?

I have been watching some bow hunting videos on youtube. When hunting with a bow, the hunter needs to get really close to the animal, sometimes less than 10 meters. It seems to me implicitly, and ...
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1answer
109 views

How does an octopus eye react in free fall?

according to Wikipedia: Attached to the brain are two special organs, called statocysts, that allow the octopus to sense the orientation of its body relative to horizontal. An autonomic response ...
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0answers
345 views

How fast the human eye can [temporarily] change its color?

I know that human eye can change its color during lifetime because of disease or medication (similar question on Biology.SE). And I know that it may change depending on the lighting. But I saw ...
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1answer
504 views

Relaxing Eyes when using Virtual-Reality-Glasses?

Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image or focus on an object as its distance varies (eye focusing). For distant vision, the ciliary ...
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1answer
793 views

How many people in the world have bad eyesight?

I was watching this ted.ed episode and heard it was around 500,000 but that didn't sound right-- does anyone know?
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1answer
5k views

Why do we go blind for a few seconds after switching off the light?

At night, when I switch off the lights, I always seem to go blind for a while. The room becomes pitch black and I am unable to see anything. After a while, however, my vision slowly recovers and I ...
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1answer
185 views

What is the rationale for the complex eye structure? [closed]

The eye is a lens that focuses rays of light from a limited spectrum, after which the the image is turned over to the brain receptors that interpret it (beginning with turning it the right side up ...
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1answer
3k views

Explanation of the ‘cherry red spot' in Tay Sachs disease

In Tay Sachs disease, a hallmark symptom is a cherry red spot in the macula of the eye surrounded by a halo of white. I understand that the ganglion cells, which are higher in numbers around the ...
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1answer
688 views

Does our brain contain an innate function about closing only one eye?

I wasn't sure where to post this, but biology seemed fitting for me. Sorry if I'm wrong. I was wondering why, when we close both our eyes and look at light, it is clear we can see the light even ...
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0answers
5k views

Why do I see the world in blue when I open my eyes? [closed]

So I was standing outside, waiting for the train. I was tired so I closed my eyes for a while. Then when I opened them, the world was a lot more blue than it normally is - why is this? I tried it a ...
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7answers
7k views

Why can't we see in low light if staring long enough?

For me it seems reasonable that if I kept my gaze on a fixed point in a room with low light, a progressively brighter and better picture would appear before my eyes, just like a camera can see in the ...
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0answers
29 views

Did the number of rods changed from ancient time?

Correct me if I am wrong, but I know that rods work under limited light conditions only. But now we are in a world that always have lights everywhere unlike ancient time when humans had to deal with ...
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1answer
39 views

A limit to birds affinity for high vantage points [closed]

Birds seem to have a natural affinity for high vantage points, including power wires, the tops of trees, and the sides and tops of buildings. However I presume the top of the Burj Khalifa is not ...
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1answer
1k views

Why do we blink instead of winking each eye independently?

Question Why do we blink both eyes at the same time rather than winking each eye as needed? Why would winking independently be better? The benefit would be a minor improvement whereby a person ...